The technical portion of the work of an optician consists in mounting a pair of ophthalmic lenses on the frame selected by the future wearer. To do this, the optician needs to shape each lens, which operation consists in modifying the outline of the lens to adapt the lens to the frame and/or to the desired lens shape.
Conventionally, shaping comprises two main operations comprising an edging operation (often referred to as “roughing”) and a finishing operation that depends on the type of frame.
Edging consists in eliminating the unwanted peripheral portion of the ophthalmic lens in question, so as to bring its outline, which is generally initially circular, down to the arbitrary outline of the rim or the surround of the frame, or merely to the desired esthetic shape when the frame is of the rimless type. This edging operation is usually followed by a chamfering operation which consists in rounding or chamfering the two sharp edges surrounding the edged lens.
The finishing operation depends on the type of frame. With a rimmed frame, a beveling operation is performed that consists in shaping a ridge that is usually referred to as a bevel. The bevel is designed to be engaged in a corresponding groove, commonly known as a bezel, that is formed in the rim or surround of the eyeglass frame in which the lens is to be mounted. When the frame is of the rimless type, the shaping of the lens and optionally the rounding of its sharp edges (chamfering) are followed by appropriate drilling of the lenses so as to enable the temples and the nose bridge of the rimless frame to be fastened thereto. Finally, when the frame is of the half-rimmed type with nylon string, the chamfering is accompanied by a grooving operation that consists in forming a groove in the edge face of the lens, the groove serving to receive the nylon string of the frame that serves to press the lens against the rigid portion thereof.
Usually, the lens is shaped on a numerically controlled grinder that possesses means for holding the lens and for driving it in rotation, together with a plurality of working tools suitable for the various operations that are to be performed.
Usually the working tools comprise in particular a roughing grindwheel and a beveling grindwheel that are mounted on a common rotary drive shaft that constitutes the main working module. The drilling, grooving, and chamfering tools, and also special tools for machining certain types of lens, such as strongly curved lenses, are disposed on other distinct working modules.
Such a machine occupies a large amount of space and is expensive because it requires at least one motor to be provided per working module.
In a particular embodiment shown in its FIG. 2, document FR 2 614 227 proposes combining some of the above-mentioned working tools on a common rotary tool-carrier that is mounted to turn about an axis of rotation. The working tools are also mounted to rotate about distinct tool axes that are substantially parallel to the axis of rotation of the tool-carrier. According to the teaching of that document, the working tools mounted on the tool-carrier are solely the tools for shaping the periphery of the lens and the freedoms of movement of those working tools to move relative to the lens for machining are few.
The variety of lens-processing operations that can be performed with that tool-carrier is therefore limited.